1. Field of the Invention
This invention relates to electric razors, and more particularly to electric razors of the type incorporating a perforated stationary cutting foil and an internal, motor-driven blade.
2. Description of the Related Art
Stationary foil/rotating blade shavers are well known in the art. Typically, this type of electric razor has a rectangular bar-shaped body with the foil-cutter arranged along one edge of the body. U.S. Pat. Nos. 4,894,912 and 5,014,428 are examples of this common configuration. A barrel shaped cutter includes blades arranged on its outside surface and rotates against the inside surface of a perforated arc shaped foil. Hairs passing through the perforations are sheared by passing blades. The position and orientation of the cutter relative to the bar-shaped body complicate application of rotational motion to the cutter. Typically, belts or gear drives are used to transmit rotational energy provided by an electric motor to one or the other end of the cutter. The delicacy and complexity of these drive arrangement complicates assembly and reduces the reliability of the typical prior art electric razor.
In addition, the typical prior art configuration makes it difficult to both transmit rotational energy to the blade and maintain an appropriate cutting interface between the inside surface of the foil and the blade. To achieve a clean shave, the contact pressure between the blade and the inside surface of the foil, i.e., at the cutting interface, must be consistent. The cutting interface is exposed to forces produced by the drive mechanism as well as force exerted on the foil by the user. These forces, which may be intermittent and variable, have a tendency to alter the relationship between the foil and the blade. The typical prior art electric razor incorporates complex mechanisms to regulate the xe2x80x9cfeelxe2x80x9d of the foil to the user""s face, while maintaining a proper cutting interface between the blade and the foil. Such mechanisms are difficult to assemble, expensive to manufacture and prone to malfunction.
If the cutting interface, i.e., the relationship between the inside surface of the foil and the rotating blade, is not sufficiently close, hairs protruding through the foil will be pulled instead of caught. Conversely, if the blade rubs on the inside surface of the foil with excessive force, heat will be generated and blades will wear prematurely.
A preferred embodiment of a motor-driven razor in accordance with the present invention re-aligns the motor and cutter on a common axis. This arrangement makes a simplified drive and suspension system possible. The cutter is resiliently mounted for rotation between a drive motor shaft and an accessory drive stud by flexible shafts. The flexible shafts are coil springs that permit the cutter to move off-axis in response to force transverse to the axis of rotation and spring back when the force is removed. The resiliently mounted cutter rotates against the inside surface of a resiliently mounted cutting foil. The cutting interface between the cutting foil inside surface and blades mounted to the cutter is maintained while the cutter and cutting foil are permitted to move in response to forces produced by normal use of the motor driven razor. The motor-driven razor may be equipped with an optional nose hair trimmer driven by the accessory drive stud.
The overall construction of a motor-driven razor in accordance with the present invention is dramatically simplified in comparison with the prior art. This simplified construction also reduces manufacturing costs. The realignment of components results in a more compact appliance that can be conveniently placed in a shirt pocket, for example. The resulting motor-driven razor is inexpensive, yet effective.
It is an object of the present invention to provide a new and improved motor-driven razor that overcomes the deficiencies of the prior art.
Another object of the present invention is to provide a new and improved motor-driven razor of compact and efficient design.
A further object of the present invention is to provide a new and improved motor-driven razor of reduced complexity and increased reliability.
These and other objects, features and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments in conjunction with the accompanying drawings.